Add crc32c checksum
[fio.git] / README
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1fio
2---
3
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4fio is a tool that will spawn a number of threads or processes doing a
5particular type of io action as specified by the user. fio takes a
6number of global parameters, each inherited by the thread unless
7otherwise parameters given to them overriding that setting is given.
8The typical use of fio is to write a job file matching the io load
9one wants to simulate.
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11
12Source
13------
14
15fio resides in a git repo, the canonical place is:
16
6b3eccb1 17git://git.kernel.dk/fio.git
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18
19The http protocol also works, path is the same.
2b02b546 20
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21Snapshots are frequently generated and they include the git meta data as
22well. You can download them here:
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23
24http://brick.kernel.dk/snaps/
25
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26Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository for
27SUSE variants, you can find them here:
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28
29http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
30
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31Dag Wieƫrs has RPMs for Red Hat related distros, find them here:
32
33http://dag.wieers.com/rpm/packages/fio/
34
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35Mandriva has integrated fio into their package repository, so installing
36on that distro should be as easy as typing 'urpmi fio'.
37
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39Mailing list
40------------
41
42There's a mailing list associated with fio. It's meant for general
43discussion, bug reporting, questions - basically anything that has to
44do with fio. An automated mail detailing recent commits is automatically
45sent to the list at most daily. The list address is fio-devel@kernel.dk,
46subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
47
48
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49Building
50--------
51
52Just type 'make' and 'make install'. If on FreeBSD, for now you have to
5f421004 53specify the FreeBSD Makefile with -f and use gmake (not make), eg:
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5f421004 55$ gmake -f Makefile.Freebsd && gmake -f Makefile.FreeBSD install
bbfd6b00 56
edffcb96 57Likewise with OpenSolaris, use the Makefile.solaris to compile there.
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58The OpenSolaris make should work fine. This might change in the
59future if I opt for an autoconf type setup.
bbfd6b00 60
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61If your compile fails with an error like this:
62
63 CC gettime.o
64In file included from fio.h:23,
65 from gettime.c:8:
66os/os.h:15:20: error: libaio.h: No such file or directory
67In file included from gettime.c:8:
68fio.h:119: error: field 'iocb' has incomplete type
69make: *** [gettime.o] Error 1
70
71Check that you have the libaio development package installed. On RPM
72based distros, it's typically called libaio-devel.
73
bbfd6b00 74
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75Command line
76------------
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77
78$ fio
ee56ad50 79 --debug Enable some debugging options (see below)
b4692828 80 --output Write output to file
062c6022 81 --timeout Runtime in seconds
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82 --latency-log Generate per-job latency logs
83 --bandwidth-log Generate per-job bandwidth logs
84 --minimal Minimal (terse) output
85 --version Print version info and exit
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86 --help Print this page
87 --cmdhelp=cmd Print command help, "all" for all of them
cca73aa7 88 --showcmd Turn a job file into command line options
062c6022 89 --readonly Turn on safety read-only checks, preventing writes
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90 --eta=when When ETA estimate should be printed
91 May be "always", "never" or "auto"
01f06b63 92 --section=name Only run specified section in job file
2b386d25 93 --alloc-size=kb Set smalloc pool to this size in kb (def 1024)
e592a06b 94
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95
96Any parameters following the options will be assumed to be job files,
97unless they match a job file parameter. You can add as many as you want,
98each job file will be regarded as a separate group and fio will stonewall
99its execution.
972cfd25 100
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101The --readonly switch is an extra safety guard to prevent accidentically
102turning on a write setting when that is not desired. Fio will only write
103if rw=write/randwrite/rw/randrw is given, but this extra safety net can
104be used as an extra precaution. It will also enable a write check in the
105io engine core to prevent an accidental write due to a fio bug.
106
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107The debug switch allows adding options that trigger certain logging
108options in fio. Currently the options are:
109
110 process Dump info related to processes
111 file Dump info related to file actions
112 io Dump info related to IO queuing
113 mem Dump info related to memory allocations
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114 blktrace Dump info related to blktrace setup
115 verify Dump info related to IO verification
116 all Enable all debug options
811a0d06 117 random Dump info related to random offset generation
a3d741fa 118 parse Dump info related to option matching and parsing
cd991b9e 119 diskutil Dump info related to disk utilization updates
5e1d306e 120 job:x Dump info only related to job number x
bd6f78b2 121 ? or help Show available debug options.
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122
123You can specify as many as you want, eg --debug=file,mem will enable
bd6f78b2 124file and memory debugging.
ee56ad50 125
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126The section switch is meant to make it easier to ship a bigger job file
127instead of several smaller ones. Say you define a job file with light,
128moderate, and heavy parts. Then you can ask fio to run the given part
129only by giving it a --section=heavy command line option. The section
130option only applies to job sections, the reserved 'global' section is
131always parsed and taken into account.
132
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133Fio has an internal allocator for shared memory called smalloc. It
134allocates shared structures from this pool. The pool defaults to 1024k
135in size, and can grow to 32 pools. If running large jobs with randommap
136enabled it can run out of memory, in which case the --alloc-size switch
137is handy for starting with a larger pool size.
138
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139
140Job file
141--------
142
71bfa161 143See the HOWTO file for a more detailed description of parameters and what
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144they mean. This file contains the terse version. You can describe big and
145complex setups with the command line, but generally it's a lot easier to
71bfa161 146just write a simple job file to describe the workload. The job file format
4661f3d0 147is in the ini style format, as that is easy to read and write for the user.
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148
149The job file parameters are:
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01452055 151 name=x Use 'x' as the identifier for this job.
61697c37 152 description=x 'x' is a text description of the job.
ebac4655 153 directory=x Use 'x' as the top level directory for storing files
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154 filename=x Force the use of 'x' as the filename for all files
155 in this thread. If not given, fio will make up
156 a suitable filename based on the thread and file
157 number.
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158 rw=x 'x' may be: read, randread, write, randwrite,
159 rw (read-write mix), randrw (read-write random mix)
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160 rwmixcycle=x Base cycle for switching between read and write
161 in msecs.
162 rwmixread=x 'x' percentage of rw mix ios will be reads. If
163 rwmixwrite is also given, the last of the two will
164 be used if they don't add up to 100%.
165 rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
166 rwmixread.
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167 rand_repeatable=x The sequence of random io blocks can be repeatable
168 across runs, if 'x' is 1.
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169 size=x Set file size to x bytes (x string can include k/m/g)
170 ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
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171 posixaio for POSIX aio, solarisaio for Solaris
172 native async IO, sync for regular read/write io,
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173 psync for regular pread/pwrite io, vsync for regular
174 readv/writev (with queuing emulation) mmap for mmap'ed
175 io, syslet-rw for syslet driven read/write, splice for
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176 using splice/vmsplice, sg for direct SG_IO io, net
177 for network io, or cpuio for a cycler burner load. sg
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178 only works on Linux on SCSI (or SCSI-like devices, such
179 as usb-storage or sata/libata driven) devices. Fio also
180 has a null io engine, which is mainly used for testing
181 fio itself.
182
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183 iodepth=x For async io, allow 'x' ios in flight
184 overwrite=x If 'x', layout a write file first.
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185 nrfiles=x Spread io load over 'x' number of files per job,
186 if possible.
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187 prio=x Run io at prio X, 0-7 is the kernel allowed range
188 prioclass=x Run io at prio class X
189 bs=x Use 'x' for thread blocksize. May include k/m postfix.
190 bsrange=x-y Mix thread block sizes randomly between x and y. May
191 also include k/m postfix.
192 direct=x 1 for direct IO, 0 for buffered IO
193 thinktime=x "Think" x usec after each io
194 rate=x Throttle rate to x KiB/sec
195 ratemin=x Quit if rate of x KiB/sec can't be met
196 ratecycle=x ratemin averaged over x msecs
197 cpumask=x Only allow job to run on CPUs defined by mask.
d2e268b0 198 cpus_allowed=x Like 'cpumask', but allow text setting of CPU affinity.
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199 fsync=x If writing with buffered IO, fsync after every
200 'x' blocks have been written.
201 end_fsync=x If 'x', run fsync() after end-of-job.
ebac4655 202 startdelay=x Start this thread x seconds after startup
03b74b3e 203 runtime=x Terminate x seconds after startup. Can include a
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204 normal time suffix if not given in seconds, such as
205 'm' for minutes, 'h' for hours, and 'd' for days.
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206 offset=x Start io at offset x (x string can include k/m/g)
207 invalidate=x Invalidate page cache for file prior to doing io
795407ca 208 sync=x Use sync writes if x and writing buffered IO.
ebac4655 209 mem=x If x == malloc, use malloc for buffers. If x == shm,
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210 use shared memory for buffers. If x == mmap, use
211 anonymous mmap.
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212 exitall When one thread quits, terminate the others
213 bwavgtime=x Average bandwidth stats over an x msec window.
214 create_serialize=x If 'x', serialize file creation.
215 create_fsync=x If 'x', run fsync() after file creation.
f6cbb269 216 unlink If set, unlink files when done.
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217 loops=x Run the job 'x' number of times.
218 verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
219 use crc32 for verifies. md5 is 'safer', but crc32 is
220 a lot faster. Only makes sense for writing to a file.
bac39e0e 221 For other types of checksumming, see HOWTO.
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222 stonewall Wait for preceeding jobs to end before running.
223 numjobs=x Create 'x' similar entries for this job
224 thread Use pthreads instead of forked jobs
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225 zonesize=x
226 zoneskip=y Zone options must be paired. If given, the job
227 will skip y bytes for every x read/written. This
228 can be used to gauge hard drive speed over the entire
229 platter, without reading everything. Both x/y can
230 include k/m/g suffix.
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231 iolog=x Open and read io pattern from file 'x'. The file must
232 contain one io action per line in the following format:
233 rw, offset, length
234 where with rw=0/1 for read/write, and the offset
235 and length entries being in bytes.
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236 write_iolog=x Write an iolog to file 'x' in the same format as iolog.
237 The iolog options are exclusive, if both given the
238 read iolog will be performed.
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239 write_bw_log Write a bandwidth log.
240 write_lat_log Write a latency log.
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241 lockmem=x Lock down x amount of memory on the machine, to
242 simulate a machine with less memory available. x can
243 include k/m/g suffix.
b6f4d880 244 nice=x Run job at given nice value.
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245 exec_prerun=x Run 'x' before job io is begun.
246 exec_postrun=x Run 'x' after job io has finished.
da86774e 247 ioscheduler=x Use ioscheduler 'x' for this job.
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248 cpuload=x For a CPU io thread, percentage of CPU time to attempt
249 to burn.
ba0fbe10 250 cpuchunks=x Split burn cycles into pieces of x usecs.
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253Author
254------
255
aae22ca7 256Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
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257of the Linux IO subsystem and schedulers. He got tired of writing
258specific test applications to simulate a given workload, and found that
259the existing io benchmark/test tools out there weren't flexible enough
260to do what he wanted.
261
aae22ca7 262Jens Axboe <axboe@kernel.dk> 20060905
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